Effects of sublingual immunotherapy for dust mite on Th 17 / Treg cells in children with asthma

Objective: observing the clinical effects of dust mite sublingual immunotherapy (SLIT) on children with asthma, changes of Th17 / Treg cells and related cytokines in order to investigate the possible pathological mechanism of immune tolerance induced by SLIT. Methods: Sixty children with asthma allergic to dust mites were included, divided into SLIT group (n=30) and non-SLIT group (n=30). Clinical symptoms of asthma in each group had been scored before, 1 year and 2 years after treatment. Meanwhile we also evaluated the proportion of Th17 and CD4 ⁺ CD25 ⁺ Treg cells in peripheral blood using flow cytometry. Besides, cell culture supernatant was collected to detect the changes of IL-6, IL-10 and IL-17 levels. Results: We found that in SLIT group, asthma symptom and drug use score, Th17 cell percentages, IL-6 and IL-17 levels have significantly decreased throughout the study period (p < 0.05), while FEV1%, Treg cell percentages and IL-10 level have prominently increased throughout the study period (p < 0.05). By contrast, in non-SLIT group, asthma symptom score, lung function, Th17 cell percentages, IL-6 and IL-17 levels have all significantly improved, but on the whole lower than SLIT group (p < 0.05). However, we have observed no statistical differences in drug use score, Treg cell percentages, IL-10 level for non-SLIT group throughout the study period. Conclusions: SLIT of Dust mite drops could change T immune cell profiles whereas improve asthma symptoms. SLIT might reverse the functional imbalance of Th 17 / Treg cells and induce immune tolerance by upregulating Treg cell function and downregulating Th17 cell function.